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