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