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