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