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