One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,7)(3,6,8,4)(9,10,14,18)(11,15,21,23)(12,16,22,20)(13,17,24,19)(25,26,32,35)(27,36,40,33)(28,30,29,39)(31,34,38,37)(1,3)(2,6)(4,7)(5,8)(9,11)(10,15)(12,17)(13,20)(14,21)(16,24)(18,23)(19,22)(25,27)(26,33)(28,37)(29,34)(30,38)(31,39)(32,40)(35,36) involution — undirected(1,2)(3,4)(5,7)(6,8)(9,12)(10,16)(11,19)(13,15)(14,22)(17,21)(18,20)(23,24)(25,28,32,29)(26,30,35,39)(27,37,40,34)(31,33,38,36)(1,4,5,6)(2,3,7,8)(9,12)(10,16)(11,17)(13,23)(14,22)(15,24)(18,20)(19,21)(25,29,32,28)(26,30,35,39)(27,34,40,37)(31,33,38,36)(1,4)(2,3)(5,6)(7,8)(9,11)(10,15)(12,19)(13,16)(14,21)(17,22)(18,23)(20,24)(25,30)(26,29)(27,38)(28,35)(31,40)(32,39)(33,34)(36,37) involution — undirected(1,2)(3,6)(4,8)(5,7)(9,13)(10,17)(11,20)(12,15)(14,24)(16,21)(18,19)(22,23)(25,31,32,38)(26,34,35,37)(27,39,40,30)(28,33,29,36)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.