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