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