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