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