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