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