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