One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,6)(3,5,7,8)(9,10,14,18)(11,15,21,16)(12,13,17,23)(19,20,22,24)(25,26,31,36)(27,37,39,32)(28,33,35,30)(29,34,40,38)(3,7)(5,8)(9,11)(10,15)(12,19)(13,20)(14,21)(16,18)(17,22)(23,24)(25,26)(27,32)(28,33)(29,38)(30,35)(31,36)(34,40)(37,39) involution — undirected(1,2)(3,5)(4,6)(7,8)(9,11,14,21)(10,15,18,16)(12,19,17,22)(13,20,23,24)(25,27,31,39)(26,32,36,37)(28,40,35,29)(30,38,33,34)(9,11)(10,16)(12,22)(13,20)(14,21)(15,18)(17,19)(23,24)(25,28,31,35)(26,33,36,30)(27,29,39,40)(32,38,37,34)(1,3)(2,5)(4,7)(6,8)(9,12)(10,13)(11,19)(14,17)(15,20)(16,24)(18,23)(21,22)(25,29)(26,34)(27,28)(30,32)(31,40)(33,37)(35,39)(36,38) involution — undirected(1,2)(3,5)(4,6)(7,8)(9,13)(10,17)(11,20)(12,18)(14,23)(15,22)(16,19)(21,24)(25,30,31,33)(26,35,36,28)(27,38,39,34)(29,37,40,32)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.