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