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