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