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