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