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