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